High-throughput deposition of a voltage-tunable dielectric material
View Patent ↗High-throughput deposition of a voltage-tunable dielectric material onto a substrate comprising a conductive electrode is provided. Respective gradients in at least two grain size defining parameters of the deposition are simultaneously provided, the respective gradients occurring for a first time period thereby producing a smoothly changing columnar crystalline habit of the voltage-tunable dielectric material. When the first time period has ended, the deposition continues for a second time period where the grain size defining parameters are held constant. In particular, the smoothly changing columnar crystalline habit of the voltage-tunable dielectric material is intentionally distorted by simultaneously providing the respective gradients in the in at least two grain size defining parameters of the deposition.
1. A method of deposition of a voltage-tunable dielectric material onto a substrate comprising a conductive electrode, the method comprising:
simultaneously providing respective gradients in at least two grain size defining parameters of the deposition, the respective gradients occurring for a first time period thereby producing a smoothly changing columnar crystalline habit of the voltage-tunable dielectric material, a first grain size defining parameter, of the at least two grain size defining parameters, comprises substrate temperature, a starting substrate temperature in the first time period being in a range of about 20° C. to about 300° C. and an ending substrate temperature in the first time period being in a range of about 600° C. to about 1000° C., and a second grain size defining parameter, of the at least two grain size defining parameters, comprises one or more of deposition power, and pressure of a deposition chamber in which the deposition is occurring; and,
when the first time period has ended, continuing deposition for a second time period where the grain size defining parameters are held constant.
2. The method of claim 1 , wherein a film of the voltage-tunable dielectric material formed on the conductive electrode during the deposition is polycrystalline.
3. The method of claim 1 , wherein the starting substrate temperature in the first time period is below a stress relief temperature of the conductive electrode.
4. The method of claim 1 , wherein when the deposition comprises sputtering, and the second grain size defining parameter comprises the deposition power, a starting sputtering power in the first time period is about 0 W/cm 2 and an ending sputtering power in the first time period is in a range of about 0.7 W/cm 2 to about 2.8 W/cm 2 .
5. The method of claim 1 , wherein when the second grain size defining parameter comprises the pressure of the deposition chamber in which the deposition is occurring, a starting pressure in the first time period is in a range of about 0.2 Pa to about 2 Pa and an ending pressure in the first time period is in a range of about 0.1 Pa to about 1 Pa.
6. The method of claim 1 , wherein when the second grain size defining parameter comprises the pressure of the deposition chamber in which the deposition is occurring, the pressure one of: decreases over the first time period or increases over the first time period.
7. The method of claim 1 , wherein the deposition comprises is one or more of: sputtering, magnetron sputtering, CVD (chemical vapour deposition), PECVD (plasma-enhanced chemical vapour deposition), and MOCVD metalorganic chemical vapour deposition).
8. The method of claim 1 , wherein one or more of the respective gradients occur in one or more steps during the first time period.
9. The method of claim 1 , wherein one or more of the respective gradients comprise a temporary pause in a change of the at least two grain size defining parameters during the first time period.
10. The method of claim 1 , wherein the first time period is in a range of about 50% to about 100% of the second time period.
11. The method of claim 1 , further comprising depositing a second conductive electrode on the voltage-tunable dielectric material after the second time period.
12. The method of claim 11 , further comprising repeating deposition of the voltage-tunable dielectric material onto the second conductive electrode, including: simultaneously providing further respective gradients in at least two grain size defining parameters of the deposition, the further respective gradients occurring for a third time period; when the third time period has ended, continuing deposition for a fourth time period where the grain size defining parameters are held constant; and depositing a third conductive electrode on the voltage-tunable dielectric material after the fourth time period.
13. The method of claim 1 , further comprising forming a capacitor on the substrate of one or more layers of the voltage-tunable dielectric material.
14. The method of claim 1 , wherein the smoothly changing columnar crystalline habit comprises columns of the voltage-tunable dielectric material changing from columns of a first width adjacent the conductive electrode to columns of a second width larger than the first width distal the conductive electrode.
15. The method of claim 1 , wherein the voltage-tunable dielectric material comprises one or more of a ferroelectric material, a perovskite material, a pyrochlore material, barium strontium titanate (BST), lead zirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT), strontium bismuth tantalate (SBT), lithium niobate, bismuth lanthanum titanate (BLT), and lead scandium titanate.
16. A system for depositing a voltage-tunable dielectric material onto a substrate comprising a conductive electrode, the system comprising:
a deposition chamber; a substrate holder configured to hold the substrate; a substrate temperature control device; a pressure control device configured to control pressure in the deposition chamber; a power control device configured to control deposition power; and a computing device configured to control the substrate temperature control device, the pressure control device, and the power control device to:
simultaneously provide respective gradients in at least two grain size defining parameters of the deposition, the respective gradients occurring for a first time period thereby producing a smoothly changing columnar crystalline habit of the voltage-tunable dielectric material, a first grain size defining parameter, of the at least two grain size defining parameters, comprises the substrate temperature, a starting substrate temperature in the first time period being in a range of about 20° C. to about 300° C. and an ending substrate temperature in the first time period being in a range of about 600° C. to about 1000° C., and a second grain size defining parameter, of the at least two grain size defining parameters, comprises one or more of the deposition power, and the pressure of the deposition chamber; and,
when the first time period has ended, continue deposition for a second time period where the grain size defining parameters are held constant.